A trisection is a way of writing a smooth 4-manifold as a union of 4-handlebodies with a specified intersection along 3-handlebodies, generalizing a Heegaard splitting. The fundamental groups of the pieces, together with the inclusion maps, form a diagram called a group trisection. We will see examples of these group trisections, and how they reflect the operations among manifold trisections, like connected sums and stabilization. We will then sketch a proof that group trisections up to isomorphism, classify manifold trisections up to diffeomorphism, after an appropriate stabilization.
Graduate Student Geometry-Topology Seminar
Monday, April 3, 2017 - 3:15pm
Jackson (McFeeley) Goodman
University of Pennsylvania